The Temnospondyls are similar or identical to the Labyrinthodonts minus the Lepospondyls. It is probably an evolutionary grade, not monophyletic. It is convenient to use, because all these early amphibia were so different from present-day amphibia.[1][2]p169 Many in the early Permian looked more like reptiles because they were adapted to life in a drier climate. Nevertheless, they were amphibians, and many larval stages have been found.

Fossils are known from the larval stage, metamorphosis, and maturity.[2]p184 Most temnospondyls were semiaquatic, although some were almost fully terrestrial, returning to the water only to breed. These temnospondyls were some of the first vertebrates fully adapted to life on land. Although temnospondyls are considered amphibians, many had characteristics such as scales, claws, and armour-like bony plates which modern amphibians do not have.